title: Detecting treatment effects with combinations of the ADAS-cog items in patients with mild and moderate Alzheimer's disease.
abstract: OBJECTIVE
  When complex cognitive functions are measured with multi-item scales like the Alzheimer's Disease Assessment Scale - cognitive subscale (ADAS-cog), it seems valuable information can be lost due to combination of the ADAS-cog items results into a total score. We hypothesized, that an analysis of the results of different ADAS-cog item combinations may reveal drug treatment effects in distinct cognitive domains and/or enhance the sensitivity to detect such treatment effects. Here, we present a novel approach called 'subsetting analysis' for assessment of drug treatment effects with multi-item scales, like the ADAS-cog.
  
  
  METHODS
  The subsetting approach is a mathematical algorithm designed to select and group scale items in a subset detecting drug treatment effects in a particular study population. The approach was applied in a post-hoc analysis of ADAS-cog results from two randomized, placebo-controlled and double-blind clinical trials with memantine in mild to moderate Alzheimer's disease (AD). The subsetting analysis of the ADAS-cog combined database aimed at selecting the scale items showing no worsening at study end compared to baseline due to memantine treatment in mild AD (Mini-Mental State Examination (MMSE >19)) patients.
  
  
  RESULTS
  Two ADAS-cog subsets were finally revealed by the analysis: a subset of five ADAS-cog items, identified as most sensitive to memantine effects in mild AD patients, and a subset of six ADAS-cog items shown to detect significant memantine effects in moderate AD patients.
  
  
  CONCLUSIONS
  The subsetting approach of analyzing ADAS-cog data is a powerful alternative for gaining information about drug effects on cognitive performance in mild and moderate AD patients.
authors.affiliation: Geriatric Psychiatry Centre, Alexian Hospital Maria-Hilf, Krefeld and Department of Psychiatry and Psychotherapy, University of Duesseldorf, Germany. ralf.ihl@maria-hilf.de
authors.forename: Ralf
authors.initials: R
authors.lastname: Ihl
authors.forename: Steven
authors.initials: S
authors.lastname: Ferris
authors.forename: Philippe
authors.initials: P
authors.lastname: Robert
authors.forename: Bengt
authors.initials: B
authors.lastname: Winblad
authors.forename: Serge
authors.initials: S
authors.lastname: Gauthier
authors.forename: Frank
authors.initials: F
authors.lastname: Tennigkeit
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000544:Alzheimer Disease / Q000188:drug therapy* / Q000523:psychology; D003071:Cognition / Q000187:drug effects*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000188:drug therapy; D015259:Dopamine Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008559:Memantine / Q000627:therapeutic use; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales / Q000592:standards*
chemical_list: D015259:Dopamine Agents; D008559:Memantine